There is modified the slave IO thread to maintain a copy of the master's binlog as it writes the relay log. The copy means the file has the same name and same contents. When this is done, slave can transparently failover between master and slaves with mirror the binlog.

When this is first enabled, the slave must download all of the current binlog. This can take some time. New events are not appended to the relay log until this has finished.

Parameters:

rpl_mirror_binlog_enabled enables this

required option log-bin-index

sync-mirror-binlog is equivalent to sync-binlog but for the mirror binlog

New commands:

These commands allow fast promotion of a slave to a master. It is fast because it can be done without restarting the slave.